1. Field of the Invention
The present invention relates generally to apparatus for separating flat products from a pile of flat products, and in particular to an apparatus for separating flat products from a pile of flat products, the apparatus including a lift hook movable from a closing position to an opening position wherein the lift hook supports the bottom of a pile of flat products in its closing position and includes an air channel for applying air through the channel.
2. Background Information
In the technology of building books, including booklets, magazines, periodicals, and the like, the use of collating systems is well known. These systems typically have a transporting device on which individual flat products, such as signatures or sheets, are gathered to build a book-block set, which then is finished and bound. Typically, a number of feeders are arranged along the transporting device, each of the hoppers including a feeding mechanism for feeding an individual flat product from a pile of signatures onto the transporting device, in order to gradually build up the book-block set or to insert a supplement sheet into a pocket of a pocket feeder or into a newspaper arranged in the pocket. Such feeding mechanisms typically employ a sheet-separating device for separating a sheet or other single flat product from a pile of flat products which is arranged in each hopper. The single flat products are drawn from the pile at its bottom end.
A sheet-separating device of this kind is described, for example, in U.S. Pat. No. 3,988,016. This document describes a high-speed paper inserting apparatus for insertion of supplements into newspapers. The inserts are placed to form a stack and a vacuum gripping member grips the lowermost insert from the stack and carries it to a pair of nip rollers which transport the insert to an opened newspaper. A single sheet requires a different sucker stroke than a 120-page or pre-inserted section. The different sucker motion requirements are due to the way the sheets or sections have to be positioned and controlled for proper singulation.
Generally, the bottom of the stack is supported by a platform, a so-called signature table having a recess for allowing a sucker to draw a single product from the lowermost end of the pile of products. When the sucker does not contact the pile of products the pile is supported by a movable hook, as shown in U.S. Pat. No. 4,157,692.
These known sheet separating devices however suffer from the disadvantage that during working, especially with thin clumsy signatures, double-pulling or bowing may occur which may lead to a stop of the machine.
It is an object of the present invention to provide a sheet-separating device having an improved lift hook. It is also an object of the present invention to provide an improved separation process of the lowermost product of the pile of products associated with a sheet-separating device.
The present invention provides an apparatus for separating flat products from a pile of flat products, the apparatus including a lift hook movable from a closing position to an opening position and supporting the bottom of a pile of flat products in its closing position wherein the lift hook defines an air channel therein for supplying air through the channel.
The air may be supplied to the air channel continuously or at timed intervals.
The air supplied to the air channel may exit the air channel at an outlet opposite a bottom of the pile of flat products so as to project one or more air streams from the lift hook.
The present invention also provides an apparatus for separating flat products from a pile of flat products, the apparatus including a lift hook movable from a closing position to an opening position and supporting the bottom of a pile of flat products in its closing position; and an air tube for supplying air to an outlet opposite a bottom of the pile of flat products so as to project at least one air stream therefrom.
The one or more air streams may act to support the pile of flat products.
The one or more air streams may act to support the bottommost product at a sucker adapted to draw a bottommost product of the pile of products from the pile.
The one or more air streams may act to help separate a bottommost product from the pile of products as the bottommost product is being drawn from the pile by a sucker.
The one or more air streams may include a first and a second air stream, the first and the second air streams being independently actuatable.
The flat products may include include signatures or sheets.
The present invention also provides a method for separating flat products from a pile of flat products, the method including providing a lift hook movable from a closing position to an opening position and supporting the bottom of a pile of flat products in its closing position, the lift hook defining an air channel therein; and supplying air through the air channel.
The apparatus and method according to the present invention enable improved separation of the bottommost sheet from pile of sheets associated with a sheet-separating device.